The invention concerns a clutch.
In the operation of, for example, soil milling machines, an important problem has become the rapid wear of the clutches. The occurrence of torques of different magnitudes in milling work is a highly important problem. In the present patent application, an improvement is suggested for the problem stated above.
It is suggested in the present patent application that, when an overload acts upon a brake disk by the intermediate of a cardan shaft, the clutch slips at the friction joint between the brake disk and the brake pads and cuts off the excessively high torque peak. When the torque is lowered to a level lower than the corresponding torque that is held by the friction force, the clutch starts holding again. Thus, the clutch just cuts off the peaks, but holds directly after the torque has become lower. The normal force is supplied to the brake pads that form the friction joint, for example, by means of a fluid pressure supplied from a tractor. In such a case, the brake pads are pressed with a force against the clutch flange. The brake pads and their brake calipers are coupled with the shaft B, and the clutch disk is coupled with the shaft A, respectively. Rotation is permitted between the shafts A and B. Further, the shafts A and B are favourably supported on each other revolvingly by means of a support bearing. The device in accordance with the invention can be used either as a normal clutch or as an overload clutch or as both. When the pressure is discharged from the brake, the clutch slips immediately, i.e. the connection of rotation drive from the drive shaft A to the driven shaft B is cut off.
In the commonest embodiment of the present invention, the pressure circuit passing to the brake cylinders is filled to a certain pressure level, which is maintained by pressure accumulators. Said pressure level in said circuit determines the torque at which the clutch starts slipping. In said embodiment, the clutch is employed exclusively as an overload clutch in order to protect the power transmission from excessive torques.
In a second embodiment of the invention, in connection with the hub part of the shaft B, additionally a connector piece 50 is used, which is coupled with the hub part 11 of the shaft B. In the solution in accordance with the invention, a pressure fluid is passed, for example, from a tractor first into the connector piece and after that into the revolving hub part 11. From the hub part the fluid is passed through a bore further to the cylinders of the brake device, placed in the brake caliper/calipers at the brake disks. By means of the fluid pressure, the brake cylinders press the brake pads into contact with the clutch disk.
In the connector part in accordance with the invention, there is/are a bearing or bearings between the hub part and the connector part. Favourably, pressure seals are also employed in order that the pressurized fluid could be passed without leakages from the bore in the connector piece further into the bore provided in the hub part 11 of the shaft B.
The overload clutch in accordance with the invention comprises a hub part, whose central bore is connected with the shaft of the device that is driven, for example a milling drum. The tool is attached from its shaft to the centre hole in the hub part, and rotation of the tool and the hub part in relation to one another is prevented by means of a groove joint. To the hub part, a connector part in accordance with the invention has been attached, through which the fluid pressure is passed first into the hub part and after that to the cylinders in the brake caliper at the brake disks.
Further, from a bore in the outer face of the hub part, pipes pass to the brake cylinders of the brake device. The output shaft of the driving machine, for example a tractor, is coupled with the clutch disk of the clutch. When the preset maximal torque is exceeded, the overload clutch cuts off said torque portions in excess of the maximal torque mentioned above, and the clutch slips. In such a case, between the brake pads connected with the hub part and the clutch disk, rotation is permitted. When the maximal torque is not exceeded, the rotation drive is transferred from the shaft A to the shaft B.
In accordance with the invention, from the fluid system of, for example, a tractor, the pressurized fluid is passed through the connector in accordance with the invention into the bore provided in the hub part and further, through the hub part, to the brake cylinders, in which connection the brake pads can be pressed with the desired force into contact with the clutch flange of the driving shaft. The overload clutch in accordance with the present invention operates as an overload protection and/or as a clutch device and/or as a brake device.
The clutch in accordance with the invention is characterized in what is stated in the patent claims.